Diamond Harbour is a small settlement on Banks Peninsula, New Zealand on the south side of Lyttelton Harbour.
The greater Diamond Harbour area also includes the nearby settlements of Church Bay, Charteris Bay and Purau. A ferry connects Diamond Harbour to Lyttelton from where buses depart to downtown Christchurch.
The name Diamond Harbour reputedly comes from the resemblance of sunlight on the water to the shining of diamonds.